Improved thermal stability and contact of antimony film by the interlayer HfO₂

The thermal stability was one of the primary obstacles hindering the development of phase-change memory. In this paper, Sb/HfO₂ multilayer phase-change films were prepared by multilayer composite method. The transition process of Sb/HfO₂ multilayer films from amorphous to crystalline state was studied by in-situ heating. With the decrease of the thickness of Sb layer, the crystallization temperature of Sb/HfO₂ increased significantly. At the same time, the data retention temperature for 10 years increased from 14 °C of pure antimony to 147 °C of Sb/HfO₂. The bandgap became wider and the surface became smoother. The existence of a large number of Sb microcrystals inhibited the phase transformation process. Compared with single-layer Sb film, Sb/HfO₂ multilayer film had smaller volume change before and after phase transformation. The results showed that the addition of HfO₂ interlayer significantly enhanced the amorphous thermal stability of Sb and improved the effective contact between the phase-change layer and the electrode. Sb/HfO₂ multilayer film was a potential phase-change film with high stability and good reliability.